Do you have a rotary, directional antenna? If so, can you "peak" the noise in a particular direction?
I've found the best way to rid myself of noise on six meters is to have a high (above ground), directional, rotary antenna. If there's a noise source in the neighborhood, the beam helps me to find it an potentially eliminate it. And if I cannot, then at least I can aim the beam in some other direction where the noise is nulled.
Trying to work "weak signals" (like SSB) on six meters with a non-directional antenna is certainly difficult.
WB2WIK/6